sorry if it looks like I'm hackin on you,
but if you are new, and don't know how to use gargnome
(which is practicaly a script to download and compile
the sources needed to run gnome2.6)
you probably don't know how to compile a programm either.
That's not something to worry about,
but you should first try your skills
on a small project, or single programm.
The gnome projekt is HUGE, with lots of dependencies.
If the gargnome script breaks on you,
you will have no other option then to start again (installing gnome2.6)
Just wait until fedora releases the packages.
The fact the almost no distro has gnome2.6 as an upgrade options show that it is not at all easy to get this baby up and running.
If you want to get you hands dirty,
go ahead and follow the instructions on the gargnome site,
most of the time it should work.
Just don't say I did not warn if it doesn't work :-)